The present invention relates generally to methods and apparatus for purifying semiconductor wafers, and to such methods and apparatus for cleaning and/or protecting wafers from contamination in particular.
The silicon wafers used in the production of semiconductor integrated circuits must be very clean, because even small amounts of undesirable contaminating impurities can cause complete degradation or malfunction of Integrated circuits. Thus, the wafers must be cleaned between processing steps, and once cleaned, protected from future recontamination. In silicon semiconductor production there exist a number of equipment and associated processes for silicon wafer cleaning and/or protection from contamination.
The present invention provides an improved apparatus and method for protecting silicon wafers in semiconductor processing and production.
There is therefore provided in accordance with a preferred embodiment of the present invention a method for protecting at least one wafer from contamination. The method includes heating the wafer in an apparatus for semiconductor processing having a reaction core, providing a first voltage level to the wafer, and providing a second voltage level lower than the first voltage level, near the reaction core, thereby activating the protection.
The method also includes the step of heating the wafer in a semiconductor furnace. The method additionally includes the step of operating a cooling system within the apparatus and/or pulling a vacuum within the apparatus.
There is therefore additionally provided in accordance with a preferred embodiment of the present invention an apparatus for protecting at least one wafer from external contamination. The apparatus includes a reaction core which processes the wafer, a heating element and a means for supplying an electrical potential.
The heating element is located on the outside of the reaction core and heats-up the wafer and the reaction core. The means for supplying an electrical potential supplies a first voltage level to the at least one wafer and a second voltage level, lower than the first voltage level, near the reaction core,
Preferably the reaction core is located within equipment for semiconductor production. Additionally preferably the reaction core is located within equipment for silicon wafer processing, such as a semiconductor furnace.
Preferably the apparatus also includes a cooling system which cools the reaction core. The cooling system preferably includes at least one blower. The heating element preferably has one or more IR lamps.
The apparatus additionally preferably includes a grid-shaped core collector electrode wrappable around the outside of the reaction core. The electrode is preferably formed of a thermo-stable material such as Aluchrom or Silicon Carbide.
The apparatus furthermore preferably includes a vacuum pump, which draws a vacuum within the reaction core.
There is therefore additionally provided in accordance with a preferred embodiment of the present invention, a wafer transfer device for holding a plurality of wafers within a furnace having a door. The device includes a support and at least one electrode.
The support is formed of Silicone Carbide (SiC), and has a base and a plurality of prongs. Each one of the plurality of wafers stands between a pair of the plurality of prongs. The electrode supplies an electrical potential to the support. The electrode is also preferably made from silicone carbide (SiC) and has a comb-like shape.
The device also includes a hook and a protrusion extending from the door. The hook is connected to the support and hooks to the protrusion, thereby suspending the device therefrom. Preferably the hook is made from quartz.
There is therefore additionally provided in accordance with a preferred embodiment of the present invention, a furnace which minimizes contamination of at least one silicone wafer processed therein. The furnace includes at least one feed-through interface and at least one electrode extension.
The feed-through interface passes though an associated opening in the furnace, such that the first end of the interface is outside of the furnace and the second end extends into the furnace. The first end is connectable to and electrode which receives an electrical potential.
The electrode extensions is connectable to the second end of an associated interface and extends from that feed-through interface into the furnace. The interface seals the opening and prevents electrical potential from leaking from the extension.
The furnace also includes a wafer transfer device which holds the wafer and is connectable to at least one electrode extension, thereby receiving the electrical potential therefrom.
Alternatively preferably the furnace is vertical or horizontal.
The furnace also includes a reaction core which processes the wafer. The furnace also has at least one feed-through interface passing though an associated at least one opening in the furnace door, and sealing the opening.
The furnace door preferably includes a door-insulating unit. The opening is preferably either at the top or at the bottom of the furnace.
The furnace also includes a liner which acts as a core collector fbr the contamination.
There is therefore additionally provided in accordance with a preferred embodiment of the present invention, a feed-through interface which carries an electrical potential. The interface includes conductive tip, a conductive spring, an electrode extension and a high temperature body.
The tip is connectable to a power supply which supplies the electrical potential. The spring has a first end and a second end, wherein the first end is connected to the tip. The electrode extension is connected to the second end of the spring, such that the potential of provided from the tip to the spring to the electrode extension. The high temperature body, preferably made from ceramic, surrounds the interface and prevents the electrical potential from leaking.